by-line vs avocation

by-line and avocation both are nouns.

Word	Noun	Adjective	Verb	Adverb
by-line	Yes	No	No	No
avocation	Yes	No	No	No

As nouns, by-line and avocation are synonyms defined as:

Other synonyms of by-line include hobby, pursuit, sideline, spare-time activity.

by-line (noun)	avocation (noun)
an auxiliary activity	an auxiliary activity
a line giving the name of the writer of a story or article